Endolysin OBPgpLYS

ABSTRACT

The present invention relates to a polypeptide with an amino acid sequence according to SEQ ID NO: 1 and fragments or derivatives thereof. The present invention further relates to fusion proteins comprising said polypeptide and an additional peptide stretch fused to said polypeptide at the N- or C-terminus. Moreover, the present invention relates to nucleic acid molecules encoding said polypeptide or fusion protein, vectors comprising said nucleic acid molecules and host cells comprising either said nucleic acid molecules or said vectors. In addition, the present invention relates to said polypeptide or fusion protein for use as a medicament, in particular for the treatment or prevention of Gram-negative bacterial infections, as diagnostic means, as cosmetic substance or as sanitizing agent. The present invention also relates to the use of said polypeptide or fusion protein for the treatment or prevention of Gram-negative bacterial contamination of foodstuff, of food processing equipment, of food processing plants, of surfaces coming into contact with foodstuff, of medical devices, of surfaces in hospitals and surgeries. Furthermore, the present invention relates to a pharmaceutical composition comprising said polypeptide or fusion protein.

This application is divisional of U.S. application Ser. No. 13/390,033,which was filed as a national phase application under 35 U.S.C. §371 ofInternational Application No. PCT/EP2010/062351 filed 24 Aug. 2010,which claims priority to European Application No. 09 168 527.1 filed on24 Aug. 2009. The entire text of each of the above-referenceddisclosures is specifically incorporated herein by reference withoutdisclaimer.

The sequence listing that is contained in the file named“DEBEP0112USD1_ST25.txt”, which is 139 KB (as measured in MicrosoftWindows®) and was created on Aug. 19, 2014, is filed herewith byelectronic submission and is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a polypeptide with an amino acidsequence according to SEQ ID NO: 1 and fragments or derivatives thereof.The present invention further relates to fusion proteins comprising saidpolypeptide and an additional peptide stretch fused to said polypeptideat the N- or C-terminus. Moreover, the present invention relates tonucleic acid molecules encoding said polypeptide or fusion protein,vectors comprising said nucleic acid molecules and host cells comprisingeither said nucleic acid molecules or said vectors. In addition, thepresent invention relates to said polypeptide or fusion protein for useas a medicament, in particular for the treatment or prevention ofGram-negative bacterial infections, as diagnostic means, as cosmeticsubstance or as sanitizing agent. The present invention also relates tothe use of said polypeptide or fusion protein for the treatment orprevention of Gram-negative bacterial contamination of foodstuff, offood processing equipment, of food processing plants, of surfaces cominginto contact with foodstuff, of medical devices, of surfaces inhospitals and surgeries. Furthermore, the present invention relates to apharmaceutical composition comprising said polypeptide or fusionprotein.

2. Description of Related Art

Gram-negative bacteria possess an outer membrane, with itscharacteristic asymmetric bilayer as a hallmark. The outer membranebilayer consists of an inner monolayer containing phospholipids(primarily phosphatidyl ethanolamine) and an outer monolayer that ismainly composed of a single glycolipid, lipopolysaccharide (LPS). Thereis an immense diversity of LPS structures in the bacterial kingdom andthe LPS structure may be modified in response to prevailingenvironmental conditions. The stability of the LPS layer and interactionbetween different LPS molecules is mainly achieved by the electrostaticinteraction of divalent ions (Mg²⁺, Ca²⁺) with the anionic components ofthe LPS molecule (phosphate groups in the lipid A and the inner core andcarboxyl groups of KDO). Furthermore, the dense and ordered packing ofthe hydrophobic moiety of lipid A, favored by the absence of unsaturatedfatty acids, forms a rigid structure with high viscosity. This makes itless permeable for lipophilic molecules and confers additional stabilityto the outer membrane (OM).

Various types of agents having bactericidal or bacteriostatic activityare known, e.g. antibiotics, endolysins, antimicrobial peptides anddefensins. Increasingly microbial resistance to antibiotics, however, iscreating difficulties in treating more and more infections caused bybacteria. Particular difficulties arise with infections caused byGram-negative bacteria like Pseudomonas aeruginosa andEnterobacteriaceae.

Endolysins are peptidoglycan hydrolases encoded by bacteriophages (orbacterial viruses). They are synthesized during late gene expression inthe lytic cycle of phage multiplication and mediate the release ofprogeny virions from infected cells through degradation of the bacterialpeptidoglycan. They are either β(1,4)-glycosylases (lysozymes),transglycosylases, amidases or endopeptidases. Antimicrobial applicationof endolysins was already suggested in 1991 by Gasson (GB2243611).Although the killing capacity of endolysins has been known for a longtime, the use of these enzymes as antibacterials was ignored due to thesuccess and dominance of antibiotics. Only after the appearance ofmultiple antibiotic resistant bacteria this simple concept of combatinghuman pathogens with endolysins received interest. A compelling need todevelop totally new classes of antibacterial agents emerged andendolysins used as ‘enzybiotics’—a hybrid term of ‘enzymes’ and‘antibiotics’—perfectly met this need. In 2001, Fischetti and coworkersdemonstrated for the first time the therapeutic potential ofbacteriophage Cl endolysin towards group A streptococci (Nelson et al.,2001). Since then many publications have established endolysins as anattractive and complementary alternative to control bacterialinfections, particularly by Gram positive bacteria. Subsequentlydifferent endolysins against other Gram positive pathogens such asStreptococcus pneumoniae (Loeffler et al., 2001), Bacillus anthracis(Schuch et al., 2002), S. agalactiae (Cheng et al., 2005) andStaphylococcus aureus (Rashel et al, 2007) have proven their efficacy asenzybiotics. Nowadays, the most important challenge of endolysin therapylies in the insensitivity of Gram-negative bacteria towards theexogenous action of endolysins, since the outer membrane shields theaccess of endolysins from the peptidoglycan. This currently prevents theexpansion of the range of effective endolysins to importantGram-negative pathogens.

Antimicrobial peptides (AMPs) represent a wide range of short, cationicor amphipatic, gene encoded peptide antibiotics that can be found invirtually every organism. Different AMPs display different properties,and many peptides in this class are being intensively researched notonly as antibiotics, but also as templates for cell penetratingpeptides. Despite sharing a few common features (e.g., cationicity,amphipathicity and short size), AMP sequences vary greatly, and at leastfour structural groups (α-helical, β-sheet, extended and looped) havebeen proposed to accommodate the diversity of the observed AMPconformations. Likewise, several modes of action as antibiotics havebeen proposed, and it was shown e.g. that the primary target of many ofthese peptides is the cell membrane whereas for other peptides theprimary target is cytoplasmic invasion and disruption of core metabolicfunctions. AMPs may become concentrated enough to exhibit cooperativeactivity despite the absence of specific target binding; for example, byforming a pore in the membrane, as is the case for most AMPs. However,this phenomenon has only been observed in model phospholipid bilayers,and in some cases, AMP concentrations in the membrane that were as highas one peptide molecule per six phospholipid molecules were required forthese events to occur. These concentrations are close to, if not at,full membrane saturation. As the minimum inhibitory concentration (MIC)for AMPs are typically in the low micromolar range, scepticism hasunderstandably arisen regarding the relevance of these thresholds andtheir importance in vivo (Melo et al., Nature reviews, Microbiology,2009, 245).

Defensins are a large family of small, cationic, cysteine- andarginine-rich antimicrobial peptides, found in both vertebrates andinvertebrates. Defensins are divided into five groups according to thespacing pattern of cysteines: plant, invertebrate, α-, β-, andθ-defensins. The latter three are mostly found in mammals. α-defensinsare proteins found in neutrophils and intestinal epithelia. β-defensinsare the most widely distributed and are secreted by leukocytes andepithelial cells of many kinds. θ-defensins have been rarely found sofar e.g. in leukocytes of rhesus macaques. Defensins are active againstbacteria, fungi and many enveloped and nonenveloped viruses. However,the concentrations needed for efficient killing of bacteria are mostlyhigh, i.e. in the micromolar range. Activity of many peptides may belimited in presence of physiological salt conditions, divalent cationsand serum. Depending on the content of hydrophobic amino acid residuesdefensins also show haemolytic activity.

BRIEF SUMMARY OF THE INVENTION

Thus, there is a need for new antimicrobial agents against Gram-negativebacteria.

This object is solved by the subject matter defined in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The following figures serve to illustrate the invention.

FIG. 1 shows the endolysin OBPgpLYS according to the present invention.In (A) the amino acid sequence of the endolysin OBPgpLYS (SEQ ID NO: 1)according to the present invention is depicted. In (B) the primarystructure of the OBPgpLYS comprising an additional His₆-tag is givenshowing the results of a functional analysis using BLASTp and Pfamanalysis. The predicted N-terminal peptidoglycan binding domain (PBD,amino acid residues 7-96) is underlined and the C-terminal catalyticdomain (amino acid residues 126-292) of the lysozyme-like superfamily iswritten in italics. The complete amino acid sequence of the OBPgpLYScomprising an additional His₆-tag at the C-terminus shown in (B) isdepicted in SEQ ID NO: 47.

FIG. 2 shows the nucleotide sequence (SEQ ID NO: 101) of the endolysinof phage OBP.

FIG. 3 shows the nucleotide sequence (SEQ ID NO: 3) of the endolysinOBPgpLYS (SEQ ID NO: 1) according to the present invention.

FIGS. 4A-4B show pictures of a Coomassie-stained SDS-PAGE showing theresults of the expression and purification of the unmodified endolysinOBPgpLYS (4A, SEQ ID NO: 47) and its modified endolysin variantPKOBPgpLYS (4B, SEQ ID NO: 49). The lane LMW pertains to a size marker(LMW ladder). The following three lanes pertain to protein fractions ofthe purified protein in Elution Buffer (20 mM NaH₂P0₄—NaOH pH7.4; 0.5 MNaCl; 500 mM imidazole) after Ni²⁺ affinity chromatography. The lane FTpertains to the flow through and the lane W to waste fractions. Onlyminor secondary bands are visible in the purified protein fractions,indicating the high purity of the recombinant protein (>90%).

FIGS. 5A-5F show in a graphic representation the antibacterialactivities of different compositions of unmodified OBPgpLYS (SEQ ID NO:47) and the modified PKOBPgpLYS (SEQ ID NO: 49) on several exponentialgrowing Gram-negative bacteria after an incubation at room temperatureand without shaking. Each species of Gram-negative bacteria wasincubated for 30 minutes with a composition comprising 0.5 mM EDTA butno endolysin, with a composition comprising 1.315 μM unmodified OBPgpLYSbut no EDTA, with a composition comprising 1.315 μM modified PKOBPgpLYSbut no EDTA, with a composition comprising 1.315 μM unmodified OBPgpLYSand 0.5 mM EDTA and with a composition comprising 1.315 μM modifiedPKOBPgpLYS and 0.5 mM EDTA. In FIG. 5A the antibacterial activity onEscherichia coli WK 6 cells is represented, in FIG. 5B the antibacterialactivity on Salmonella typhimurium LT2 (SGSC No 2317) cells, in FIG. 5Cthe antibacterial activity on Pseudomonas aeruginosa PAO1p cells, inFIG. 5D the antibacterial activity on Pseudomonas aeruginosa Br667cells, in FIG. 5E the antibacterial activity on Pseudomonas putida G1cells and in FIG. 5F the antibacterial activity on Burkholderiapseudomallei cells. “Δ” gives the difference of antibacterial activitybetween the respective OBPgpLYS and PKOBPgpLYS samples. The error barsrender the standard deviations of the mean.

FIG. 6 shows in a graphic representation the host specificity of theunmodified OBPgpLYS (SEQ ID NO: 47) and the modified PKOBPgpLYS (SEQ IDNO: 49). Each species of Gram-negative bacteria was incubated for 30minutes with a composition comprising each 1.315 μM unmodified OBPgpLYSor modified PKOBPgpLYS. The bar chart gives the antibacterial activitiesof the unmodified OBPgpLYS and modified OBPgpLYS on Pseudomonasaeruginosa PAO1p cells (PAO1), Escherichia coli WK6 cells (wk6),Burkholderia pseudomallei cells (Burk pseudo), Pseudomonas aeruginosaBr667 cells (Br667), Salmonella typhimurium LT2 cells (LT2) andPseudomonas putida G1 cells (Ppu G1). The error bars indicate thestandard deviations of the mean.

DETAILED DESCRIPTION OF THE INVENTION

The term “protein” as used herein refers synonymously to the term“polypeptide”. The term “protein” as used herein refers to a linearpolymer of amino acid residues linked by peptide bonds in a specificsequence. The amino-acid residues of a protein may be modified by e.g.covalent attachments of various groups such as carbohydrates andphosphate. Other substances may be more loosely associated with thepolypeptide chains, such as heme or lipid, giving rise to the conjugatedproteins which are also comprised by the term “protein” as used herein.The various ways in which the polypeptide chains fold have beenelucidated, in particular with regard to the presence of alpha helicesand beta-pleated sheets. The term “protein” as used herein refers to allfour classes of proteins being all-alpha, all-beta, alpha/beta and alphaplus beta.

The term “fusion protein” as used herein refers to an expression productresulting from the fusion of two nucleic acid sequences. Such a proteinmay be produced, e.g., in recombinant DNA expression systems. Moreover,the term “fusion protein” as used herein refers to a fusion of a firstamino acid sequence as e.g. an endolysin, with a second or further aminoacid sequence. The second or further amino acid sequence is preferably apeptide stretch, in particular a cationic peptide, a polycationicpeptide, an amphipatic peptide, a sushi peptide, a defensin, ahydrophobic peptide or an antimicrobial peptide. Preferably, said secondand/or further amino acid sequence is foreign to and not substantiallyhomologous with any domain of the first amino acid sequence.

The term “peptide stretch” as used herein refers to any kind of peptidelinked to a protein such as an endolysin. In particular the term“peptide stretch” as used herein refers to a cationic peptide, apolycationic peptide, an amphipatic peptide, a sushi peptide, adefensin, a hydrophobic peptide and/or an antimicrobial peptide.However, a peptide stretch in the meaning of the present invention doesnot refer to His₆-tags, Strep-tags, Avi-tags, Myc-tags, Gst-tags,JS-tags, cystein-tags, FLAG-tags or other tags known in the art,thioredoxin or maltose binding proteins (MBP).

The term “tag” in contrast to the term “peptide stretch” as used hereinrefers to a peptide which can be useful to facilitate expression and/oraffinity purification of a polypeptide, to immobilize a polypeptide to asurface or to serve as a marker or a label moiety for detection of apolypeptide e.g. by antibody binding in different ELISA assay formats aslong as the function making the tag useful for one of the above listedfacilitation is not caused by the positively charge of said peptide.However, the His₆-tag may, depending on the respective pH, also bepositively charged, but is used as affinity purification tool as itbinds to immobilized divalent cations and is not used as a peptidestretch according to the present invention.

The term “peptide” as used herein refers to short polypeptidesconsisting of from about 2 to about 100 amino acid residues, morepreferably from about 4 to about 50 amino acid residues, more preferablyfrom about 5 to about 30 amino acid residues, wherein the amino group ofone amino acid residue is linked to the carboxyl group of another aminoacid residue by a peptide bond. A peptide may have a specific function.A peptide can be a naturally occurring peptide or a syntheticallydesigned and produced peptide. The peptide can be, for example, derivedor removed from a native protein by enzymatic or chemical cleavage, orcan be prepared using conventional peptide synthesis techniques (e.g.,solid phase synthesis) or molecular biology techniques (see Sambrook, J.et al., Molecular Cloning: A Laboratory Manual, Cold Spring HarborPress, Cold Spring Harbor, N.Y. (1989)). Preferred naturally occurringpeptides are e.g. antimicrobial peptides, defensins, and sushi peptides.Preferred synthetically produced peptides are e.g. polycationic,amphiphatic or hydrophobic peptides. A peptide in the meaning of thepresent invention does not refer to His-tags, Strep-tags, thioredoxin ormaltose binding proteins (MBP) or the like, which are used to purify orlocate proteins.

The term “endolysin” as used herein refers to an enzyme which issuitable to hydrolyse bacterial cell walls. “Endolysins” comprise atleast one “enzymatically active domain” (EAD) having at least one of thefollowing activities: endopeptidase, N-acetyl-muramoyl-L-alanine-amidase(amidase), N-acetyl-muramidase, N-acetyl-glucosaminidase (lysozyme) ortransglycosylases. In addition, the endolysins may contain also regionswhich are enzymatically inactive, and bind to the cell wall of the hostbacteria, the so-called CBDs (cell wall binding domains). The endolysinmay contain two or more CBDs. However, the term “endolysin” as usedherein refers also to enzymes having at least one EAD but no CBDs.Generally, the cell wall binding domain is able to bind differentcomponents on the surface of bacteria. Preferably, the cell wall bindingdomain is a peptidoglycan binding domain and binds to the bacteria'speptidoglycan structure. The different domains of an endolysin can beconnected by a domain linker.

The term “domain linker” as used herein refers to an amino acid sequencefunctioning to connect single protein domains with one another. As arule domain linkers form no or only few regular secondary structure likeα-helices or β-sheets and can occupy different conformations with therespective structural context. Methods to detect domain linker andproperties of linker sequences are well known in the art as e.g.described in Bae et al., 2005, Bioinformatics, 21, 2264-2270 or George &Heringa, 2003, Protein Engineering, 15, 871-879.

The term “wild type” or “wt” as used herein refers to the amino acidsequence of the endolysin OBPgpLYS as depicted in SEQ ID NO: 86. Thenucleic acid sequence encoding the wild type endolysin OBPgpLYS isdepicted in SEQ ID NO: 101.

The term “deletion” as used herein refers to the removal of 1, 2, 3, 4,5 or more amino acid residues from the respective starting sequence.

The term “insertion” or “addition” as used herein refers to theinsertion or addition of 1, 2, 3, 4, 5 or more amino acid residues tothe respective starting sequence.

The term “substitution” as used herein refers to the exchange of anamino acid residue located at a certain position for a different one.

The term “cell wall” as used herein refers to all components that formthe outer cell enclosure of the Gram-negative bacteria and thusguarantee their integrity. In particular, the term “cell wall” as usedherein refers to peptidoglycan, the outer membrane of the Gram-negativebacteria with the lipopolysaccharide, the bacterial cell membrane, butalso to additional layers deposited on the peptidoglycan as e.g.capsules, outer protein layers or slimes.

The term “EAD” as used herein refers to the enzymatically active domainof an endolysin. The EAD is responsible for hydrolysing bacterialpeptidoglycans. It exhibits at least one enzymatic activity of anendolysin. The EAD can also be composed of more than one enzymaticallyactive module. The term “EAD” is used herein synonymously with the term“catalytic domain”.

As used herein, the term “cationic peptide” refers to a peptide havingpositively charged amino acid residues. Preferably a cationic peptidehas a pKa-value of 9.0 or greater. Typically, at least four of the aminoacid residues of the cationic peptide can be positively charged, forexample, lysine or arginine. “Positively charged” refers to the sidechains of the amino acid residues which have a net positive charge atabout physiological conditions. The term “cationic peptide” as usedherein refers also to polycationic peptides.

The term “polycationic peptide” as used herein refers to a syntheticallyproduced peptide composed of mostly positively charged amino acidresidues, in particular lysine and/or arginine residues. A peptide iscomposed of mostly positively charged amino acid residues if at leastabout 20, 30, 40, 50, 60, 70, 75, 80, 85, 90, 95 or about 100% of theamino acid residues are positively charged amino acid residues, inparticular lysine and/or arginine residues. The amino acid residuesbeing not positively charged amino acid residues can be neutrallycharged amino acid residues and/or negatively charged amino acidresidues and/or hydrophobic amino acid residues. Preferably the aminoacid residues being not positively charged amino acid residues areneutrally charged amino acid residues, in particular serine and/orglycine.

The term, “antimicrobial peptide” (AMP) as used herein refers to anypeptide that has microbicidal and/or microbistatic activity. Thus, theterm “antimicrobial peptide” as used herein refers in particular to anypeptide having anti-bacterial, anti-fungal, anti-mycotic,anti-parasitic, anti-protozoal, anti-viral, anti-infectious,anti-infective and/or germicidal, algicidal, amoebicidal, microbicidal,bactericidal, fungicidal, parasiticidal, protozoacidal, protozoicidalproperties.

The term “defensin” as used herein refers to a peptide present withinanimals, preferably mammals, more preferably humans, wherein thedefensin plays a role in the innate host defense system as thedestruction of foreign substances such as infectious bacteria and/orinfectious viruses and/or fungi. A defensin is a non-antibodymicrobicidal and/or tumoricidal protein, peptide or polypeptide.Examples for “defensins” are “mammalian defensins,” alpha-defensins,beta-defensins, indolicidin and magainins. The term “defensins” as usedherein refers both to an isolated form from animal cells or to asynthetically produced form, and refers also to variants whichsubstantially retain the cytotoxic activities of their parent proteins,but whose sequences have been altered by insertion or deletion of one ormore amino acid residues.

The term “sushi peptide” as used herein refers to complement controlproteins (CCP) having short consensus repeats. The sushi module of sushipeptides functions as a protein-protein interaction domain in manydifferent proteins. Peptides containing a Sushi domain have been shownto have antimicrobial activities.

The term “amphipathic peptide” as used herein refers to peptides havingboth hydrophilic and hydrophobic functional groups. Preferably, the term“amphipathic peptide” as used herein refers to a peptide having adefined arrangement of hydrophilic and hydrophobic groups e.g.amphipatic peptides may be e.g. alpha helical, having predominantly nonpolar side chains along one side of the helix and polar residues alongthe remainder of its surface.

The term “hydrophobic group” as used herein refers to chemical groupssuch as amino acid side chains which are substantially water insoluble,but soluble in an oil phase, with the solubility in the oil phase beinghigher than that in water or in an aqueous phase. In water, amino acidresidues having a hydrophobic side chain interact with one another togenerate a nonaqueous environment. Examples of amino acid residues withhydrophobic side chains are valine, isoleucine, leucine, methionine,phenylalanine, tryptophan, cysteine, alanine, tyrosine, histidine,threonin, serine, proline and glycine residues.

The present invention relates to new antibacterial agents againstGram-negative bacteria. In particular the present invention relates to apolypeptide comprising an amino acid sequence according to SEQ ID NO: 1or fragments or derivatives thereof. The polypeptide comprising an aminoacid sequence according to SEQ ID NO: 1 is preferably encoded by anucleotide sequence according to SEQ ID NO: 3.

The endolysin OBPgpLYS having an amino acid sequence according to SEQ IDNO: 1 has a length of 328 amino acids. It comprises a N-terminal cellwall binding domain (CBD) and a C-terminal enzymatic active domain(EAD). The N-terminal CBD is a peptidoglycan binding domain (PGB, aa7-96) having an amino acid sequence according to SEQ ID NO: 4. TheC-terminal EAD is a catalytic domain (aa 126-292) complying with thecatalytic domain of the lysozyme-like superfamily and having an aminoacid sequence according to SEQ ID NO: 5. The PGB and the catalyticdomain of the endolysin OBPgpLYS are connected by a domain linker.

Thus, preferred fragments of the polypeptide according to the presentinvention are polypeptides comprising an amino acid sequence accordingto SEQ ID NO: 4 and/or according to SEQ ID NO: 5. Another preferredfragment of the polypeptide according to the present invention comprisesan amino acid sequence according to SEQ ID NO: 69. The fragment havingan amino acid sequence according to SEQ ID NO: 69 differs from thepolypeptide having an amino acid sequence according to SEQ ID NO: 1 inthat the starting methionine residue has been deleted.

The derivatives according to the present invention are polypeptidescomprising an amino acid sequence according to SEQ ID NO: 1, 4, 5 and/or69 but having additional modification and/or alterations. Saidmodifications and/or alterations can be mutations in particulardeletions, insertions, additions, substitutions or any combinationsthereof and/or chemical changes of the amino acid residues, e.g.biotinylation, acetylation, pegylation, chemical changes of the amino-,SH- or carboxyl-groups. Said derivatives according to the presentinvention exhibit the lytic activity of the OBPgpLYS (SEQ ID NO: 1)and/or the activity of the fragments according to the present invention.Said activity can be about 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110,120, 130, 140, 150, 160, 170, 180, 190 or about 200% of the activity ofthe OBPgpLYS and/or the activity of the fragments according to thepresent invention. The activity can be measured by assays well known inthe art by a person skilled in the art as e.g. the plate lysis assay orthe liquid lysis assay which are e.g. described in (Briers et al., J.Biochem. Biophys Methods 70: 531-533, (2007)).

Preferred derivatives according to the present invention arepolypeptides comprising an amino acid sequence according to SEQ ID NO:86 and 87. Said derivatives differ from the polypeptides having an aminoacid sequence according to SEQ ID NO: 1 and SEQ ID NO: 69, respectively,in that the leucine residue has been substituted by a histidine residueat positions 325 and 324, respectively. The polypeptide comprising anamino acid sequence according to SEQ ID NO: 86 is preferably encoded bya nucleotide sequence according to SEQ ID NO: 101.

In a preferred embodiment of the present invention the polypeptide,fragment and/or derivative according to the present invention comprisesadditionally a tag such as a His₆-tag, Strep-tag, Avi-tag, Myc-tag,Gst-tag, JS-tag, cystein-tag, FLAG-tag or other tags known in the art atthe N-terminus or at the C-terminus. In a preferred embodiment of thepresent invention said tag is linked to the polypeptide, fragment and/orderivative according to the present invention at the C-terminus. Saidtag may be linked to said polypeptide, fragment and/or derivative overadditional amino acid residues. Said additional amino acid residues maybe consist of at least 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 additional aminoacid residues. In a preferred embodiment of the present invention thetag is linked to the polypeptide, fragment and/or derivative accordingto the present invention by the additional amino acid residues Leu-Gluor Lys-Gly.

In a preferred embodiment the present invention relates to polypeptidescomprising an amino acid sequence according to SEQ ID NO: 47 or SEQ IDNO: 88. The polypeptide having an amino acid sequence according to SEQID NO: 47 and SEQ ID NO: 88, respectively, comprises in comparison tothe polypeptide having an amino acid sequence according to SEQ ID NO: 1and SEQ ID NO: 86, respectively, an additional C-terminal His₆-taglinked to the C-terminus of the polypeptide having an amino acidsequence according to SEQ ID NO: 1 and SEQ ID NO: 86, respectively, bythe additional amino acid residues lysine and glycine (Lys-Gly). Thepolypeptide comprising an amino acid sequence according to SEQ ID NO: 47is preferably encoded by a nucleotide sequence according to SEQ ID NO:48. The polypeptide comprising an amino acid sequence according to SEQID NO: 88 is preferably encoded by a nucleotide sequence according toSEQ ID NO: 89.

A further aspect of the present invention are fusion proteins composedof an polypeptide, fragment and/or derivative according to the presentinvention and a peptide stretch fused to the polypeptide, fragmentand/or derivative according to the present invention at the N- orC-terminus.

The peptide stretch of the fusion protein according to the presentinvention is preferably covalently bound to the polypeptide, fragmentand/or derivative according to the present invention. Preferably, saidpeptide stretch consists of at least 5, more preferably at least of 6,7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43,44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79,80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97,98, 99 or at least 100 amino acid residues. Especially preferred is apeptide stretch comprising about 5 to about 100 amino acid residues,about 5 to about 50 or about 5 to about 30 amino acid residues. Morepreferred is a peptide stretch comprising about 6 to about 42 amino acidresidues, about 6 to about 39 amino acid residues, about 6 to about 38amino acid residues, about 6 to about 31 amino acid residues, about 6 toabout 25 amino acid residues, about 6 to about 24 amino acid residues,about 6 to about 22 amino acid residues, about 6 to about 21 amino acidresidues, about 6 to about 20 amino acid residues, about 6 to about 19amino acid residues, about 6 to about 16 amino acid residues, about 6 toabout 14 amino acid residues, about 6 to about 12 amino acid residues,about 6 to about 10 amino acid residues or about 6 to about 9 amino acidresidues. Preferably, the peptide stretch is no tag such as a His₆-tag,Strep-tag, Avi-tag, Myc-tag, Gst-tag, JS-tag, cystein-tag, FLAG-tag orother tags known in the art and no thioredoxin or maltose bindingproteins (MBP). However, the peptide stretch may comprise in additionsuch tag or tags or the like, which are used to purify or locateproteins.

Preferably, the peptide stretch has the function to lead the fusionprotein according to the present invention through the outer membrane ofGram-negative bacteria but has no or only low activity when administeredwithout being fused to the polypeptide, fragment and/or derivativeaccording to the present invention. The function to lead the fusionprotein through the outer membrane of Gram-negative bacteria is causedby the potential of the membrane or LPS disrupting activity of saidpeptide stretch. To determine whether a peptide stretch has membrane orLPS disrupting activity said peptide stretch can be fused to apolypeptide according to the present invention as e.g. described in theExamples of the present invention. Subsequently, the antibacterialactivity of the fusion protein consisting of the polypeptide accordingto the present invention and the peptide stretch to be tested can becompared to the polypeptide according the present invention having nopeptide stretch as also described in the Examples of the presentinvention and e.g. shown in FIGS. 5A-5F and 6. Preferably, said testsmay be carried out on Escherichia coli WK6 and/or Pseudomonas aeruginosaPAO1p cells as used in the Examples of the present invention. In casethe fusion protein has an increased antibacterial activity in comparisonto the polypeptide according to the present invention without saidpeptide stretch for at least one of the tested gram-negative bacteriaspecies then said peptide stretch has a membrane or LPS disruptingactivity. Preferably, the antibacterial activity (in logarithmic units(=log₁₀N₀/N_(i))) of the polypeptide according to the present inventionis increased by at least about 5%, more preferably by at least about10%, by a peptide stretch having membrane or LPS disrupting activity.

In one aspect of the present invention the fused peptide stretch is anamphipathic peptide, which comprises one or more of the positivelycharged amino acid residues of lysine, arginine and/or histidine,combined to one or more of the hydrophobic amino acid residues ofvaline, isoleucine, leucine, methionine, phenylalanine, tryptophan,cysteine, alanine, tyrosine, histidine, threonin, serine, proline and/orglycine. Side chains of the amino acid residues are preferably orientedin order that cationic and hydrophobic surfaces are clustered atopposite sides of the peptide. Preferably, more than about 30, 40, 50,60 or 70% of the amino acids in said peptide are positively chargedamino acids. Preferably, more than about 30, 40, 50, 60 or 70% of theamino acid residues in said peptide are hydrophobic amino acid residues.Advantageously, the amphipathic peptide is fused at the N-terminaland/or the C-terminal end of the polypeptide, fragment and/or derivativeaccording to the present invention having cell wall degrading activity,thus enhancing the amphipathicity of the latter proteins.

In a preferred embodiment at least about 30, 40, 50, 60 or 70% of thesaid amino acid residues of the amphipathic peptide are either arginineor lysine residues and/or at least about 30, 40, 50, 60 or 70% of thesaid amino acid residues of the amphipathic peptide are of thehydrophobic amino acid residues valine, isoleucine, leucine, methionine,phenylalanine, tryptophan, cysteine, alanine, tyrosine, histidine,threonin, serine, proline and/or glycine.

Preferred amphipatic peptides are Pleurocidin according to SEQ ID NO: 6,Cecropin P1 according to SEQ ID NO: 7, Buforin II according to SEQ IDNO: 8, Buforin I according to SEQ ID NO: 9 and Magainin according to SEQID NO: 10. Further preferred amphipatic peptides are Cathelidicine e.g.LL-37 according to SEQ ID NO: 11.

In a further aspect of the present invention the fused peptide stretchis an antimicrobial peptide, which comprises a positive net charge andaround 50% hydrophobic amino acid residues. The antimicrobial peptidesare amphipathic, with a length of about 12 to about 50 amino acidresidues.

Preferred antimicrobial peptides are listed in the following table.

Peptide Sequence LL-37 LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTESSEQ ID NO: 11 SMAP-29 RGLRRLGRKIAHGVKKYGPTVLRIIRIAG SEQ ID NO: 12Indolicidin ILPWKWPWWPWRR SEQ ID NO: 13 Protegrin RGGRLCYCRRRFCVCVGRSEQ ID NO: 14 Cecropin P1 SWLSKTAKKLENSAKKRISEGIAIAIQGGPR SEQ ID NO: 7Magainin GIGKFLHSAKKFGKAFVGEIMNS SEQ ID NO: 10 PleurocidinGWGSFFKKAAHVGKHVGKAALTHYL SEQ ID NO: 6 Cecropin AGGLKKLGKKLEGAGKRVFNAAEKALPVVAGAKALRK SEQ ID NO: 15 (A. aegypti)Cecropin A GWLKKIGKKIERVGQHTRDATIQGLGIPQQAANVAATARG SEQ ID NO: 16(D. melanogaster) Buforin II TRSSRAGLQFPVGRVHRLLRK SEQ ID NO: 8Sarcotoxin IA GWLKKIGKKIERVGQHTRDATIQGLGIAQQAANVAATAR SEQ ID NO: 17Ascaphine GIKDWIKGAAKKLIKTVASHIANQ SEQ ID NO: 50 ApidaecineANRPVYIPPPRPPHPRL SEQ ID NO: 51 Nigrocine GLLSKVLGVGKKVLCGVSGLVCSEQ ID NO: 52 Pseudin 1 GLNTLKKVFQGLHEAIKLINNHVQ SEQ ID NO: 53 Parasin 1KGRGKQGGKVRAKAKTRSS SEQ ID NO: 72 Lycotoxin IWLTALKFLGKHAAKKLAKQQLSKLSEQ ID NO: 73 Ranalexin FLGGLIVPAMICAVTKKC SEQ ID NO: 117 MelittinGIGAVLKVLT TGLPALISWI KRKRQQ SEQ ID NO: 119

In a further aspect of the present invention the fused peptide stretchis a sushi peptide which is described by Ding J L, Li P, Ho B Cell MolLife Sci. 2008 April; 65(7-8):1202-19. The Sushi peptides: structuralcharacterization and mode of action against Gram-negative bacteria.

Preferred sushi peptides are sushi peptides S1 and S3 and multiplesthereof; FASEB J. 2000 September; 14(12): 1801-13.

In a further aspect of the present invention the fused peptide stretchis a defensin, preferably Cathelicidine, Cecropin P1, Cecropin A orMagainin II.

In a further aspect of the present invention the fused peptide stretchis a hydrophobic peptide, preferably having the amino acid sequencePhe-Phe-Val-Ala-Pro (SEQ ID NO:18).

Further preferred peptide stretches are listed in the following table:

Alpha 4 PNRAKRVITTFRT SEQ ID NO: 68 Artilysin1 GFFIPAVILPSIAFLIVPSEQ ID NO: 70 Artilysin2 GKPGWLIKKALVFKKLIR SEQ ID NO: 71 RPLKRLA WLBU2KRWVKRVKRVKRWVKRVV SEQ ID NO: 118 variant RVVKRWVKR

In one aspect of the present invention the fused peptide stretch is ancationic and/or polycationic peptide, which comprises one or more of thepositively charged amino acid residues of lysine, arginine and/orhistidine, in particular of lysine and/or arginine. Preferably, morethan about 20, 30, 40, 50, 60, 70, 75, 80, 85, 90, 95 or 99% of theamino acid residues in said peptide stretch are positively charged aminoacid residues, in particular lysine and/or arginine residues. Especiallypreferred are peptide stretches consisting of about 100% positivelycharged amino acid residues, in particular arginine and/or lysineresidues, wherein preferably about 60% to about 70% of said positivelycharged amino acid residues are lysine residues and about 30% to about40% of said positively charged amino acid residues are arginineresidues. More preferred is a peptide stretch consisting of about 100%positively charged amino acid residues, in particular arginine and/orlysine residues, wherein preferably about 64% to about 68% of saidpositively charged amino acid residues are lysine and about 32% to about36% of said positively charged amino acid residues are arginine. Peptidestretches consisting of either only arginine or only lysine are alsopreferred.

Especially preferred are cationic and/or polycationic peptide stretchescomprising at least one motif according to SEQ ID NO: 19 (KRKKRK). Inparticular cationic peptide stretches comprising at least 2, 3, 4, 5, 6,7, 8, 9, 10, 11, 12, 13, 14, 15, 16 or 17 motifs according to SEQ ID NO:19 (KRKKRK) are preferred. More preferred are cationic peptide stretchescomprising at least one KRK motif (lys-arg-lys), preferable at least 2,3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22,23, 24, 25, 26, 27, 28, 29, 30, 31, 32 or 33 KRK motifs.

In another preferred embodiment of the present invention the cationicpeptide stretch comprises beside the positively charged amino acidresidues, in particular lysine and/or arginine residues, neutrallycharged amino acid residues, in particular glycine and/or serineresidues. Preferred are cationic peptide stretches consisting of about70% to about 100%, or about 80% to about 95%, or about 85% to about 90%positively charged amino acid residues, in particular lysine and/orarginine residues and of about 0% to about 30%, or about 5% to about20%, or about 10% to about 20% neutrally charged amino acid residues, inparticular glycine and/or serine residues. Preferred are polypeptidestretches consisting of about 4% to about 8% serine residues, of about33% to about 36% arginine residues and of about 56% to about 63% lysineresidues. Especially preferred are polypeptide stretches comprising atleast one motif according to SEQ ID NO: 40 (KRXKR), wherein X is anyother amino acid residue than lysine, arginine and histidine. Especiallypreferred are polypeptide stretches comprising at least one motifaccording to SEQ ID NO: 41 (KRSKR). More preferred are cationicstretches comprising at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,13, 14, 15, 16, 17, 18, 19 or about 20 motifs according to SEQ ID NO: 40(KRXKR) or SEQ ID NO: 41 (KRSKR).

Also preferred are polypeptide stretches consisting of about 9 to about16% glycine residues, of about 4 to about 11% serine residues, of about26 to about 32% arginine residues and of about 47 to about 55% lysineresidues. Especially preferred are polypeptide stretches comprising atleast one motif according to SEQ ID NO: 42 (KRGSG). More preferred arecationic stretches comprising at least about 2, 3, 4, 5, 6, 7, 8, 9, 10,11, 12, 13, 14, 15, 16, 17, 18, 19 or about 20 motifs according to SEQID NO: 42 (KRGSG).

In another preferred embodiment of the present invention the cationicpeptide stretch comprises beside the positively charged amino acidresidues, in particular lysine and/or arginine residues, hydrophobicamino acid residues, in particular valine, isoleucine, leucine,methionine, phenylalanine, tryptophan, cysteine, alanine, tyrosine,histidine, threonin, serine, proline and/or glycine residues. Preferredare cationic peptide stretches consisting of about 70% to about 100%, orabout 80% to about 95%, or about 85% to about 90% positively chargedamino acid residues, in particular lysine and/or arginine residues andof about 0% to about 30%, or about 5% to about 20%, or about 10% toabout 20% hydrophobic amino acid residues in particular valine,isoleucine, leucine, methionine, phenylalanine, tryptophan, cysteine,alanine, tyrosine, histidine, threonin, serine, proline and/or glycineresidues.

Especially preferred are peptide stretches selected from the groupconsisting of the following sequences:

Peptide stretch length SEQ ID NO:  KRKKRK 6 SEQ ID NO: 19 KRKKRKKRK 9SEQ ID NO: 20 RRRRRRRRR 9 SEQ ID NO: 21 KKKKKKKK 8 SEQ ID NO: 22KRKKRKKRKK 10 SEQ ID NO: 23 KRKKRKKRKKRK 12 SEQ ID NO: 24 KRKKRKKRKKRKKR14 SEQ ID NO: 25 KKKKKKKKKKKKKKKK 16 SEQ ID NO: 26 KRKKRKKRKKRKKRKKRKK19 SEQ ID NO: 27 RRRRRRRRRRRRRRRRRRR 19 SEQ ID NO: 28KKKKKKKKKKKKKKKKKKK 19 SEQ ID NO: 29 KRKKRKKRKRSKRKKRKKRK 20SEQ ID NO: 30 KRKKRKKRKRSKRKKRKKRKK 21 SEQ ID NO: 31KRKKRKKRKKRKKRKKRKKRK 21 SEQ ID NO: 32 KRKKRKKRKRGSGKRKKRKKRK 22SEQ ID NO: 33 KRKKRKKRKRGSGSGKRKKRKK 24 SEQ ID NO: 34 RKKRKKRKKRKKRKKRKKRKKRKK 25 SEQ ID NO: 35 RKK KRKKRKKRKRSKRKKRKKRKRS 31SEQ ID NO: 36 KRKKRKKRK KRKKRKKRKRGSGSGKRKKRKK 38 SEQ ID NO: 37RKGSGSGKRKKRKKRK KRKKRKKRKKRKKRKKRKKRKK 39 SEQ ID NO: 38RKKRKKRKKRKKRKKRK KRKKRKKRKRSKRKKRKKRKRS 42 SEQ ID NO: 39KRKKRKKRKRSKRKKRKKRK

Especially preferred is a fusion protein comprising a polypeptide,fragment and/or derivative according to the present invention and apeptide stretch having an amino acid sequence according to SEQ ID NO:20. More preferred are fusion proteins having an amino acid sequenceaccording to SEQ ID NO: 43 and SEQ ID NO: 115. Also preferred are fusionproteins an amino acid sequence according to SEQ ID NO: 49 and SEQ IDNO: 116. The fusion proteins having an amino acid sequence according toSEQ ID NO: 49 and SEQ ID NO: 116, respectively, comprises in comparisonto the fusion proteins having an amino acid sequence according to SEQ IDNO: 43 and SEQ ID NO: 115, respectively, an additional C-terminalHis₆-tag linked to the C-terminus of the fusion protein having an aminoacid sequence according to SEQ ID NO: 43 and SEQ ID NO: 115,respectively, by the additional amino acid residues lysine and glycine(Lys-Gly). The fusion proteins having an amino acid sequence accordingto SEQ ID NO: 43 and SEQ ID NO: 115 and SEQ ID NO: 49 and SEQ ID NO:116, respectively, differ in that the fusion proteins having an aminoacid sequence according to SEQ ID NO: 115 and SEQ ID NO: 116 has each asubstitution of the leucine residue to a histidine residue at position336.

In another preferred embodiment of the present invention the peptidestretches of the fusion protein according to the present inventioncomprise modifications and/or alterations of the amino acid sequences.Such alterations and/or modifications may comprise mutations such asdeletions, insertions and additions, substitutions or combinationsthereof and/or chemical changes of the amino acid residues, e.g.biotinylation, acetylation, peglyation, chemical changes of the amino-,SH- or carboxyl-groups.

A fusion protein according to the present invention as already outlinedabove is composed of

-   -   (a) an polypeptide, fragment and/or derivative according to the        present invention, and    -   (b) a peptide stretch fused to said polypeptide, fragment and/or        derivative at the N- or C-Terminus, and optionally    -   (c) a tag, such as a His₆-tags, Strep-tags, Avi-tags, Myc-tags,        Gst-tags, JS-tags, cystein-tags, FLAG-tags or other tags known        in the art at the N- or C-Terminus.

In case the peptide stretch is fused to the polypeptide, fragment and/orderivative according to the present invention at the C-Terminus, thefusion protein comprises the additional tag preferably at theN-terminus. In an especially preferred embodiment of the presentinvention the peptide stretch is fused to the polypeptide, fragmentand/or derivative according to the present invention at the N-Terminus.In case said fusion protein comprises an additional tag said tag ispreferably at the C-terminus.

The two and three components of the fusion protein, respectively, asoutlined above may be linked to each other over additional amino acidresidues e.g. due to cloning reasons. Moreover, the peptide stretch maybe linked to the starting methionine residue of the fusion protein byadditional amino acid residues. Said additional amino acid residues maybe consist of at least 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 additional aminoacid residues. In a preferred embodiment of the present invention thepeptide stretch is linked to the polypeptide, fragment and/or derivativeaccording to the present invention by the additional amino acid residuesGly-Ser or Gly-Gly-Ser. The additional amino acid residues linking thestarting methionine residue and the peptide stretch are preferablyGly-Ser. In case the fusion protein additionally comprises a tag, thepolypeptide, fragment and/or derivative according to the presentinvention is preferably linked to said tag by the additional amino acidresidues Leu-Glu or Lys-Gly.

The following table exemplifies the above outlined assembly ofspecifically preferred fusion proteins according to the presentinvention listed in the first column starting with the startingmethionine residue at the N-terminus in the second column and endingwith the optional tag at the C-terminus in the last column:

polypeptide, Fusion fragment, protein First derivative according toamino peptide according to the present acid additional stretchadditional the present additional invention residue amino acid (SEQ IDamino acid invention amino acid tag (SEQ ID NO:) (N-term) residues NO:)residues (SEQ ID NO:) residues (C-term) SEQ: 43 Met — SEQ: 20 Gly-SerSEQ: 69 — — SEQ: 49 Met — SEQ: 20 Gly-Ser SEQ: 69 Lys-Gly HIS₆-tagSEQ: 54 Met — SEQ: 50 Gly-Ser SEQ: 87 — — SEQ: 55 Met — SEQ: 50 Gly-SerSEQ: 87 Leu-Glu HIS₆-tag SEQ: 56 Met — SEQ: 51 Gly-Ser SEQ: 87 — —SEQ: 57 Met — SEQ: 51 Gly-Ser SEQ: 87 Leu-Glu HIS₆-tag SEQ: 58 Met —SEQ: 52 Gly-Ser SEQ: 87 — — SEQ: 59 Met — SEQ: 52 Gly-Ser SEQ: 87Leu-Glu HIS₆-tag SEQ: 60 Met — SEQ: 53 Gly-Ser SEQ: 87 — — SEQ: 61 Met —SEQ: 53 Gly-Ser SEQ: 87 Leu-Glu HIS₆-tag SEQ: 62 Met — SEQ: 17 Gly-SerSEQ: 87 — — SEQ: 63 Met — SEQ: 17 Gly-Ser SEQ: 87 Leu-Glu HIS₆-tagSEQ: 64 Met — SEQ: 12 Gly-Ser SEQ: 87 — — SEQ: 65 Met — SEQ: 12 Gly-SerSEQ: 87 Leu-Glu HIS₆-tag SEQ: 66 Met — SEQ: 15 Gly-Ser SEQ: 87 — —SEQ: 67 Met — SEQ: 15 Gly-Ser SEQ: 87 Leu-Glu HIS₆-tag SEQ: 74 MetGly-Ser SEQ: 68 Gly-Ser-Ser SEQ: 87 — — SEQ: 75 Met Gly-Ser SEQ: 68Gly-Ser-Ser SEQ: 87 Lys-Gly HIS₆-tag SEQ: 76 Met Gly-Ser SEQ: 69Gly-Ser-Ser SEQ: 87 — — SEQ: 77 Met Gly-Ser SEQ: 69 Gly-Ser-Ser SEQ: 87Lys-Gly HIS₆-tag SEQ: 78 Met Gly-Ser SEQ: 70 Gly-Ser-Ser SEQ: 87 — —SEQ: 79 Met Gly-Ser SEQ: 70 Gly-Ser-Ser SEQ: 87 Lys-Gly HIS₆-tag SEQ: 80Met Gly-Ser SEQ: 71 Gly-Ser-Ser SEQ: 87 — — SEQ: 81 Met Gly-Ser SEQ: 71Gly-Ser-Ser SEQ: 87 Lys-Gly HIS₆-tag SEQ: 82 Met Gly-Ser SEQ: 72Gly-Ser-Ser SEQ: 87 — — SEQ: 83 Met Gly-Ser SEQ: 72 Gly-Ser-Ser SEQ: 87Lys-Gly HIS₆-tag SEQ: 84 Met Gly-Ser SEQ: 73 Gly-Ser-Ser SEQ: 87 — —SEQ: 85 Met Gly-Ser SEQ: 73 Gly-Ser-Ser SEQ: 87 Lys-Gly HIS₆-tagSEQ: 115 Met — SEQ: 20 Gly-Ser SEQ: 87 — — SEQ: 116 Met — SEQ: 20Gly-Ser SEQ: 87 Lys-Gly HIS₆-tag

The present invention further relates to an isolated nucleic acidmolecule encoding the polypeptide, fragment, derivative and/or fusionprotein according to the present invention. Especially preferredisolated nucleic acid molecules according to the present inventioncomprise a nucleic acid sequence according to SEQ ID NO: 2, 3, 48, 89 or101. The present invention further relates to a vector comprising thenucleic acid molecule according to the present invention. Said vectormay provide for the constitutive or inducible expression of saidpolypeptide, fragment, derivative and/or fusion protein according to thepresent invention.

The invention also relates to a method for obtaining said polypeptide,fragment, derivative and/or fusion proteins from a micro-organism, suchas a genetically modified suitable host cell which expresses saidpolypeptide, fragment, derivative and/or fusion proteins. Said host cellmay be a micro-organism such as bacteria or yeast or an animal cell ase.g. a mammalian cell, in particular a human cell. In one embodiment ofthe present invention the host cell is an Escherichia coli cell. Thehost may be selected due to mere biotechnological reasons, e.g. yield,solubility, costs, etc. but may be also selected from a medical point ofview, e.g. a non-pathological bacteria or yeast or human cells. Anotheraspect of the present invention is related to a method for geneticallytransforming a suitable host cell in order to obtain the expression ofthe polypeptide, fragment, derivative and/or fusion proteins accordingto the present invention, wherein the host cell is genetically modifiedby the introduction of a genetic material encoding said polypeptide,fragment, derivative and/or fusion proteins into the host cell andobtain their translation and expression by genetic engineering methodswell known by the man skilled in the art.

In a further aspect the present invention relates to a composition,preferably a pharmaceutical composition, comprising a polypeptide,fragment, derivative and/or fusion protein according to the presentinvention and/or a host transformed with a nucleic acid molecule or avector comprising a nucleotide sequence encoding a polypeptide,fragment, derivative and/or fusion protein according to the presentinvention.

In a preferred embodiment of the present invention the compositioncomprises additionally agents permeabilizing the outer membrane ofGram-negative bacteria such metal chelators as e.g. EDTA, TRIS, lacticacid, lactoferrin, polymyxin, citric acid and/or other substances asdescribed e.g. by Vaara (Agents that increase the permeability of theouter membrane. Vaara M. Microbiol Rev. 1992 September; 56(3):395-441).Also preferred are compositions comprising combinations of the abovementioned permeabilizing agents. Especially preferred is a compositioncomprising about 10 μM to about 100 mM EDTA, more preferably about 50 μMto about 10 mM EDTA, more preferably about 0.5 mM to about 10 mM EDTA,more preferably about 0.5 mM to about 2 mM EDTA, more preferably about0.5 mM to about 1 mM EDTA. Also preferred is a composition comprisingabout 0.5 mM to about 2 mM EDTA, more preferably about 1 mM EDTA andadditionally about 10 to about 100 mM TRIS.

The present invention also relates to a polypeptide, fragment,derivative and/or fusion protein according to the present inventionand/or a host transformed with a nucleic acid comprising a nucleotidesequence encoding a polypeptide, fragment, derivative and/or fusionprotein according to the present invention for use as a medicament. In afurther aspect the present invention relates to the use of apolypeptide, fragment, derivative and/or fusion protein according to thepresent invention and/or a host transformed with a vector comprising anucleic acid molecule comprising a nucleotide sequence encoding apolypeptide, fragment, derivative and/or fusion protein according to thepresent invention in the manufacture of a medicament for the treatmentand/or prevention of a disorder, disease or condition associated withGram-negative bacteria. In particular the treatment and/or prevention ofthe disorder, disease or condition may be caused by Gram-negativebacteria of bacterial groups, families, genera or species comprisingstrains pathogenic for humans or animals like Enterobacteriaceae(Escherichia, especially E. coli, Salmonella, Shigella, Citrobacter,Edwardsiella, Enterobacter, Hafnia, Klebsiella, especially K.pneumoniae, Morganella, Proteus, Providencia, Serratia, Yersinia),Pseudomonadaceae (Pseudomonas, especially P. aeruginosa, Burkholderia,Stenotrophomonas, Shewanella, Sphingomonas, Comamonas), Neisseria,Moraxella, Vibrio, Aeromonas, Brucella, Francisella, Bordetella,Legionella, Bartonella, Coxiella, Haemophilus, Pasteurella, Mannheimia,Actinobacillus, Gardnerella, Spirochaetaceae (Treponema and Borrelia),Leptospiraceae, Campylobacter, Helicobacter, Spirillum, Streptobacillus,Bacteroidaceae (Bacteroides, Fusobacterium, Prevotella, Porphyromonas),Acinetobacter, especially A. baumanii. In particular, the treatmentand/or prevention of the disorder, disease or condition may be caused byPseudomonas aeruginosa, Pseudomonas putida, Burkholderia pseudomallei,E. coli and/or Salmonella typhimurium.

The present invention further relates to a medicament comprising apolypeptide, fragment, derivative and/or fusion protein according to thepresent invention and/or a host transformed with a nucleic acidcomprising a nucleotide sequence encoding a polypeptide, fragment,derivative and/or fusion protein according to the present invention.

In a further aspect the present invention relates to a method oftreating a disorder, disease or condition in a subject in need oftreatment and/or prevention, which method comprises administering tosaid subject an effective amount of a polypeptide, fragment, derivativeand/or fusion protein according to the present invention and/or aneffective amount of a host transformed with a nucleic acid comprising anucleotide sequence encoding a polypeptide, fragment, derivative and/orfusion protein according to the present invention or a compositionaccording to the present invention. The subject may be a human or ananimal.

In particular said method of treatment may be for the treatment and/orprevention of infections of the skin, of soft tissues, the respiratorysystem, the lung, the digestive tract, the eye, the ear, the teeth, thenasopharynx, the mouth, the bones, the vagina, of wounds of bacteraemiaand/or endocarditis caused by Gram-negative bacteria, in particular bythe Gram-negative bacteria as listed above.

The dosage and route of administration used in a method of treatment (orprophylaxis) according to the present invention depends on the specificdisease/site of infection to be treated. The route of administration maybe for example oral, topical, nasopharyngeal, parenteral, intravenous,rectal or any other route of administration.

For application of a polypeptide, fragment, derivative and/or fusionprotein according to the present invention and/or an effective amount ofa host transformed with a nucleic acid comprising a nucleotide sequenceencoding a polypeptide, fragment, derivative and/or fusion proteinaccording to the present invention or a composition according to thepresent invention to a site of infection (or site endangered to beinfected) a formulation may be used that protects the active compoundsfrom environmental influences such as proteases, oxidation, immuneresponse etc., until it reaches the site of infection. Therefore, theformulation may be capsule, dragee, pill, suppository, injectablesolution or any other medical reasonable galenic formulation.Preferably, the galenic formulation may comprise suitable carriers,stabilizers, flavourings, buffers or other suitable reagents. Forexample, for topical application the formulation may be a lotion orplaster, for nasopharyngeal application the formulation may be salinesolution to be applied via a spray to the nose.

Preferably, a polypeptide, fragment, derivative and/or fusion proteinaccording to the present invention is used for medical treatment, if theinfection to be treated (or prevented) is caused by multiresistantbacterial strains, in particular by strains resistant against one ormore of the following antibiotics: streptomycin, tetracycline,cephalothin, gentamicin, cefotaxime, cephalosporin, ceftazidime orimipenem. Furthermore, a polypeptide, fragment, derivative and/or fusionprotein according to the present invention can be used in methods oftreatment by administering it in combination with conventionalantibacterial agents, such as antibiotics, lantibiotics, bacteriocins orendolysins, etc.

The present invention also relates to a pharmaceutical pack comprisingone or more compartments, wherein at least one compartment comprises oneor more polypeptide, fragment, derivative and/or fusion proteinaccording to the present invention and/or one or more hosts transformedwith a nucleic acid comprising a nucleotide sequence encoding apolypeptide, fragment, derivative and/or fusion protein according to thepresent invention or a composition according to the present invention.

In another aspect the present invention relates to a process ofpreparation of a pharmaceutical composition, said process comprisingadmixing one or more polypeptide, fragment, derivative and/or fusionprotein according to the present invention and/or one or more hoststransformed with a nucleic acid comprising a nucleotide sequenceencoding a polypeptide, fragment, derivative and/or fusion proteinaccording to the present invention with a pharmaceutically acceptablediluent, excipient or carrier.

In an even further aspect the composition according to the presentinvention is a cosmetic composition. Several bacterial species can causeirritations on environmentally exposed surfaces of the patient's bodysuch as the skin. In order to prevent such irritations or in order toeliminate minor manifestations of said bacterial pathogens, specialcosmetic preparations may be employed, which comprise sufficient amountsof the polypeptide, fragment, derivative and/or fusion protein accordingto the present invention in order to degrade already existing or freshlysettling pathogenic Gram-negative bacteria.

In a further aspect the present invention relates to the polypeptide,fragment, derivative and/or fusion protein according to the presentinvention for use as diagnostic means in medicinal, food or feed orenvironmental diagnostics, in particular as a diagnostic means for thediagnostic of bacteria infection caused in particular by Gram-negativebacteria. In this respect the polypeptide, fragment, derivative and/orfusion protein according to the present invention may be used as a toolto specifically degrade pathogenic bacteria, in particular Gram-negativepathogenic bacteria. The degradation of the bacterial cells by thepolypeptide, fragment, derivative and/or fusion protein according to thepresent invention can be supported by the addition of detergents likeTriton X-100 or other additives which weaken the bacterial cell envelopelike polymyxin B. Specific cell degradation is needed as an initial stepfor subsequent specific detection of bacteria using nucleic acid basedmethods like PCR, nucleic acid hybridization or NASBA (Nucleic AcidSequence Based Amplification), immunological methods like IMS,immunofluorescence or ELISA techniques, or other methods relying on thecellular content of the bacterial cells like enzymatic assays usingproteins specific for distinct bacterial groups or species (e.g.β-galactosidase for enterobacteria, coagulase for coagulase positivestrains).

In a further aspect the present invention relates to the use of thepolypeptide, fragment, derivative and/or fusion protein according to thepresent invention for the treatment or prevention of Gram-negativebacterial contamination of foodstuff, of food processing equipment, offood processing plants, of surfaces coming into contact with foodstuffsuch as shelves and food deposit areas and in all other situations,where pathogenic, facultative pathogenic or other undesirable bacteriacan potentially infest food material, of medical devices and of all kindof surfaces in hospitals and surgeries.

In particular, a polypeptide, fragment, derivative and/or fusion proteinof the present invention may be used prophylactically as sanitizingagent. Said sanitizing agent may be used before or after surgery, or forexample during hemodialysis. Moreover, premature infants andimmunocompromised persons, or those subjects with need for prostheticdevices may be treated with a fusion protein according to the presentinvention. Said treatment may be either prophylactically or during acuteinfection. In the same context, nosocomial infections, especially byantibiotic resistant strains like Pseudomonas aeruginosa (FQRP),Acinetobacter species and Enterobacteriaceae such as E. coli,Salmonella, Shigella, Citrobacter, Edwardsiella, Enterobacter, Hafnia,Klebsiella, Morganella, Proteus, Providencia, Serratia and Yersiniaspecies may be treated prophylactically or during acute phase with apolypeptide, fragment, derivative and/or fusion protein of the presentinvention. Therefore, a polypeptide, fragment, derivative and/or fusionprotein according to the present invention may be used as a disinfectantalso in combination with other ingredients useful in a disinfectingsolution like detergents, tensids, solvents, antibiotics, lantibiotics,or bacteriocins.

The following examples explain the present invention but are notconsidered to be limiting. Unless indicated differently, molecularbiological standard methods were used, as e.g., described by Sambrock etal., 1989, Molecular Cloning: A Laboratory Manual, 2nd edition, ColdSpring Harbor Laboratory Press, Cold Spring Harbor, N.Y.

EXAMPLE 1 Modified Endolysin Variants of Pseudomonas putida Phage OBP

OBPgpLYS having an amino acid sequence according to SEQ ID NO: 1 is amodular endolysin of 332 amino acid residues originating fromPseudomonas putida phage OBP with a putative N-terminal peptidoglycanbinding domain and a C-terminal catalytic chitinase domain. OPBgpLYShaving an amino acid sequence according to SEQ ID NO: 47 comprises incomparison to OBPgpLYS having an amino acid sequence according to SEQ IDNO: 1 an additional C-terminal His₆-tag linked to the C-terminus by theadditional amino acid residues lysin and glycin (Lys-Gly)

Purified genomic DNA of phage OBP was used as a template for theamplification of the open reading frame (ORF) of OBPgpLYS in standardPCR reaction with Pfu polymerase (Fermentas, Ontario, Canada) using thefollowing PCR parameters:

Therefore a standard 5′ primer (5′ ATGAAAAATAGCGAGAAGAAT 3′ (SEQ ID NO:44)) and a standard 3′ primer (5′ AACTATTCCGAGTGCTTTCTTTGT 3′ (SEQ IDNO: 45)) was used. To extend the 5′ end of the ORF which encodesOBPgpLYS with a gene fragment encoding the polycationic 9-mer peptideLys-Arg-Lys-Lys-Arg-Lys-Lys-Arg-Lys- (SEQ ID NO: 20) a tail PCR (withsame parameters as standard PCR above) with an extended 5′ primer (5′ATGGGATCCAAACGCAAGAAACGTAAGAAACGCAAAAAAAATAGCGAG AAGAAT 3′ (SEQ ID NO:46)) and the standard 3′ primer according to SEQ ID NO: 45 was applied.Both the original unmodified OBPgpLYS PCR fragment and the extendedfragment were ligated in the pEXP5CT/TOPO® expression vector(Invitrogen, Carlsbad, Calif., USA) by following the TA-cloning protocolof the manufacturer.

Recombinant expression of OBPgpLYS having an amino acid sequenceaccording to SEQ ID NO: 47 and PKOBPgpLYS having an amino acid sequenceaccording to SEQ ID NO: 49 is performed in exponentially growing E. coliBL21 (XDE3) pLysS cells (Invitrogen) after induction with 1 mM IPTG(isopropylthiogalactoside) at 37° C. for a period of 4 hours. Bothproteins were purified by Ni²⁺ affinity chromatography (Akta FPLC, GEHealthcare) using the C-terminal 6× His-tag, encoded by thepEXP5CT/TOPO® expression vector. The Ni²⁺ affinity chromatography isperformed in 4 subsequent steps, all on room temperature:

-   -   1. Equilibration of the Histrap HP 1 ml column (GE Healthcare)        with 10 column volumes of Washing Buffer (60 mM imidazole, 0.5        mM NaCl and 20 mM NaH₂P0₄-NaOH on pH 7.4) at a flow rate of 0.5        ml/min.    -   2. Loading of the total lysate (with wanted endolysin) on the        Histrap HP 1 ml column at a flow rate of 0.5 ml/min.    -   3. Washing of the column with 15 column volumes of Washing        Buffer at a flow rate of 1 ml/min.    -   4. Elution of bounded endolysin from the column with 10 column        volumes of Elution Buffer (500 mM imidazole, 0.5 M NaCl and 20        mM NaH₂P0₄-NaOH on pH 7.4) at a flow rate of 0.5 ml/min

The total yields of both purified recombinant proteins per liter E. coliexpression culture is shown in Table 1. The values were determined byspectrophotometric measurement of the protein concentration and thetotal volume of the purified stock solution at a wavelength of 280 nm.Purified stock solutions consisting of OBPgpLYS and PKOBPgpLYS,respectively, in Elution Buffer (20 mM NaH₂P0₄-NaOH pH7.4; 0.5 M NaCl;500 mM imidazole) were at least 90% pure as determined visually onSDS-PAGE gels.

TABLE 1  Yields of purified recombinant OBPgpLYSendolysin and its PK-modified PKOBPgpLYS per liter E. coli expressionculture. Endolysins Expression yield OBPgpLYS (SEQ ID NO: 47) 3.3 mgPKOBPgpLYS (SEQ ID NO: 49) 4.7 mg

To determine the anti-Gram-negative spectrum of the endolysins OBPgpLYSaccording to SEQ ID NO: 47 and PKOBPgpLYS according to SEQ ID NO: 49, acombination of 1.313 μM of each endolysin and 0.5 mM EDTA was tested onthe clinical multiresistant P. aeruginosa strain Br667, Pseudomonasputida G1 (host of phage OBP) and a range of other Gram-negativepathogens (P. aeruginosa PAO1p, P. aeruginosa Br667, P. putida G1,Burkholderia pseudomallei, Escherichia coli WK6 and Salmonellatyphimurium) (see Table 3). Exponential growing bacterial cells(OD_(600 nm) of 0.6) were 100-fold diluted to a final density of about10⁶ cells/ml of each strain was incubated for 30 minutes at roomtemperature without shaking with unmodified endolysin OBPgpLYS (SEQ IDNO: 47) and modified endolysin PKOBPgpLYS (SEQ ID NO: 49) each incombination without and with 0.5 mM EDTA. For incubation, the endolysinswere used each in buffer (20 mM NaH₂P0₄-NaOH pH7.4; 0.5 M NaCl; 0.5 Mimidazole) and the incubation took place at a final concentration ofendolysin of 1,313 μM. As a control each strain was also incubated for30 minutes with 0.5 mM EDTA (in same buffer as outlined above) but noendolysin. After incubation cell suspensions were diluted three times(respectively 10⁵-10⁴-10³ cells/ml) and 100 μl of each dilution wasplated out on LB-medium. The residual colonies were counted after anovernight incubation at 37° C. Based on the counted cell numbers theantibacterial activity as the relative inactivation in logarithmic units(=log₁₀N₀/N_(i) with N₀=number of untreated cells and N_(i)=number oftreated cells, both counted after incubation) was calculated (Table 2).All samples were replicated in threefold. Averages +/− standarddeviations are represented. The maximal reduction observed is dependenton the detection level of 10 cells/ml and the initial cell density.

TABLE 2 Antibacterial activity of unmodified endolysin (OBPgpLYS) andits modified endolysin variant (PKOBPgpLYS) with and without EDTA-Na₂ ondifferent exponential growing Gram-negative species in logarithmicunits. 1.313 μM 1.313 μM 0.5 mM 1.313 μM 1.313 μM OBPgpLYS +PKOBPgpLYS + EDTA OBPgpLYS PKOBPgpLYS 0.5 mM EDTA 0.5 mM EDTA P.aeruginosa 0.130 +/− 0.023 2.531 +/− 0.173 3.079 +/− 0.015 4.357 +/−1.857 >5.687 PAO1p P. aeruginosa 0.031 +/− 0.023 1.082 +/− 0.083 1.163+/− 0.063 3.144 +/− 0.223 5.272 +/− 0.573 Br667 P. putida G1 0.412 +/−0.055 0.141 +/− 0.027 0.904 +/− 0.079 4.891 +/− 0.000 >4.891Burkholderia 0.220 +/− 0.081 0.997 +/− 0.131 1.806 +/− 0.287  4.08 +/−0.301 >4.861 pseudomallei Escherichia coli 0.592 +/− 0.113 0.681 +/−0.032 1.434 +/− 0.018 1.179 +/− 0.200 1.695 +/− 0.147 WK6 Salmonella0.054 +/− 0.048 0.076 +/− 0.011 0.127 +/− 0.013 0.774 +/− 0.052 0.908+/− 0.037 typhimurium

While the global efficacy of the OBPgpLYS treatment is speciesdependent, the results in Table 2 show an added effect of the PKOBPgpLYScompared to unmodified OBPgpLYS for all bacterial species tested, bothin the absence as the presence of 0.5 mM EDTA. For Pseudomonas andBurkholderia species, a clear synergistic effect with EDTA is observedfor the PKOBPgpLYS activity.

TABLE 3 List of used Gram-negative strains Gram-negative strain SourceReference Pseudomonas aeruginosa PAO1p Burn wound isolate, Queen Pirnayet al., 2003* Astrid Hospital, Brussels Pseudomonas aeruginosa Br667Burn wound isolate, Queen Pirnay et al., 2003* Astrid Hospital, BrusselsPseudomonas putida G1 Soil isolate, Moskow Prof V. Krylov** Burkholderiapseudomallei Clinical isolate, UZ Prof J. Verhaegen*** Gasthuisberg,Leuven Escherichia coli WK6 Standard laboratory Stratagene****expression strain Salmonella typhimurium LT2 SGSC No 2317 Prof C.Michiels***** *Pirnay J P, De Vos D, Cochez C, Bilocq F, Pirson J,Struelens M, Duinslaeger L, Cornelis P, Zizi M, Vanderkelen A. (2003).Molecular epidemiology of Pseudomonas aeruginosa colonization in a burnunit: persistence of a multidrug-resistant clone and a silversulfadiazine-resistant clone. J Clin Microbiol, 41(3): 1192-1202.**State Research Institute for Genetics and Selection of IndustrialMicroorganisms, Moscow 113545, 1st Dorozhnii projezd, 1, Russia ***Afd.Experiment. Laboratoriumgeneesk., UZ Herestraat 49 - bus 7003, 3000Leuven, Belgium ****STANSSENS, P., OPSOMER, C., MCKEOWNY, M., KRAMER,W., ZABEAU, M. and FRITZ, H.-J. (1989). Efficientoligonucleotide-directed construction of mutations in expression vectorsby the gapped duplex D N A method using alternating selectable markers.NucleiC Acids Research 17, 4441-4454. *****Centr. Levensmidd.- & Microb.Technol., Kasteelpark Arenberg 23 - bus 2457, 3001 Heverlee, Belgium

EXAMPLE 2 Effect of Different EDTA Concentrations on the AntibacterialActivity of OBPgpLYS and PKOBPgpLYS

To determine the influence of EDTA on the antibacterial activity ofunmodified and modified endolysins the antibacterial activity of theunmodified OBPgpLYS endolysin (SEQ ID NO: 47) and the PKOBPgpLYSendolysin (SEQ ID NO: 49) was tested on Pseudomonas aeruginosa PAO1pcells (Pirnay J P et al. J Clin Microbiol., 41(3):1192-1202 (2003))using different concentrations of EDTA and endolysins. Exponentialgrowing bacterial cells (OD_(600 nm) of 0.6) were 100-fold diluted to afinal density of about 10⁶ cells/ml and incubated for 30 minutes at roomtemperature without shaking with unmodified endolysin OBPgpLYS (SEQ IDNO: 47) and modified endolysin PKOBPgpLYS (SEQ ID NO: 49). Forincubation, the endolysins were used each in buffer (20 mM NaH₂P0₄-NaOHpH7.4; 0.5 M NaCl; 0.5 M imidazole) at final concentrations of endolysinof 0.013 μM, 0.131 μM and 1.315 μM. Thereby, the following differentEDTA concentrations were used: 0 mM, 0.05 mM, 0.5 mM and 10 mM. As acontrol one sample was also incubated for 30 minutes with no endolysin,instead of there was buffer (20 mM NaH₂P0₄-NaOH pH7.4; 0.5 M NaCl; 0.5 Mimidazole) added. After incubation cell suspensions were diluted threetimes (respectively 10⁵-10⁴-10³ cells/ml) and 100 μl of each dilutionwas plated out on LB-medium. The residual colonies were counted after anovernight incubation at 37° C. Based on the counted cell numbers theantibacterial activity as the relative inactivation in logarithmic units(=log₁₀N₀/N_(i) with N₀=number of untreated cells and N_(i)=number oftreated cells, both counted after incubation) was calculated (Table 4).All samples were replicated in threefold. Averages +/− standarddeviations are represented. The maximal reduction observed (5.69 logunits) is dependent on the detection level of 10 cells/ml and theinitial cell density. “Δ” gives the difference of activity between therespective OBPgpLYS and PKOBPgpLYS samples.

TABLE 4 Antibacterial activity of unmodified endolysin (OBPgpLYS) andits modified endolysin variant (PKOBPgpLYS) in combination withdifferent EDTA-Na₂ concentrations on exponential growing Pseudomonasaeruginosa PAO1p cells in logarithmic units Concentration of EDTA-Na₂(in mM) 0 0.05 0.5 10 No endolysin / 0.028 +/− 0.008 0.130 +/− 0.0231.827 +/− 0.052 0.013 μM 0.956 +/− 0.110 / 4.626 +/− 0.287 / OBPgpLYS0.013 μM 0.992 +/− 0.181 / 5.204 +/− 0.000 / PKOBPgpLYS Δ 0.036   0.5780.131 μM 2.158 +/− 0.027 / 4.599 +/− 0.275 / OBPgpLYS 0.131 μM 2.529 +/−0.184 / 5.671 +/− 0.000 / PKOBPgpLYS Δ 0.371   1.072 1.315 μM 2.531 +/−0.173 2.762 +/− 0.091 4.357 +/− 1.857 4.888 +/− 0.275 OBPgpLYS 1.315 μM3.079 +/− 0.015 4.145 +/− 0.015 >5.687 >5.687 PKOBPgpLYS Δ 0.5481.383 >1.330 >0.799

As shown in Table 4 unmodified endolysin OBPgpLYS reduces cell numberssignificantly with more than 2.5 log units for 1.315 μM and with +/−1log unit for 0.013 μM, compared to the negative control. Modifiedendolysin PKOBPgpLYS results in an added 0.5 log units reduction forexponentially growing PAO1p cells. The observed antibacterial effect canbe increased to more as 5.69 log units reduction (beneath the detectionlevel) by combining PKOBPgpLYS with the outer membrane permeabilizerEDTA-Na₂ at a concentration of 0.5 and 10 mM EDTA. The difference inactivity between the unmodified OBPgpLYS and the PK-modified OBPgpLYSincreases by raising the amount of added endolysin (from 0.013-1.315 μMendolysin).

EXAMPLE 3 Cloning, Expression and Purification of an OBPgpLYS DerivativeModified with Various Peptide Stretches on the N-Terminus of theEndolysin

The OBPgpLYS derivative according to SEQ ID NO:86 is a modular endolysinoriginating from Pseudomonas putida phage OBP with an N-terminalpeptidoglycan binding and C-terminal catalytic domain. The OBPgpLYSderivative is encoded by the nucleic acid molecule according to SEQ IDNO: 101. Purified Plasmid DNA (see Example 1) was used to produce anucleic acid molecule according to SEQ ID NO: 101 with a BamH I (5′-GGATCC-3′) restriction site at the 5′-end of the nucleic acid molecule andan Xho I (5′-CTC GAG-3′) restriction site at the 3′-end of the nucleicacid molecule.

The following peptide stretches in table 5 were used for production offusion proteins with the endolysin OBPgpLYS derivative. The resultingfusion proteins are also listed in table 5.

TABLE 5 Peptide stretches and their respective nucleic acid sequence forproduction of specific fusion proteins Nucleic acid molecule Amino acidsequence of Peptide stretch encoding the peptide stretch resultingfusion protein Ascaphine SEQ ID NO: 90 SEQ ID NO: 55 (SEQ ID NO: 50)Apidaecine SEQ ID NO: 91 SEQ ID NO: 57 (SEQ ID NO: 51) Sarcotoxin IA SEQID NO: 92 SEQ ID NO: 63 (SEQ ID NO: 17) SMAP-29 SEQ ID NO: 93 SEQ ID NO:65 (SEQ ID NO: 12) Cecropin A SEQ ID NO: 94 SEQ ID NO: 67 (A. aegypti)(SEQ ID NO: 15)

The nucleic acid molecules encoding the respective peptide stretcheswere synthetically produced with a Nde I (5′-CAT ATG-3′) restrictionsite at the 5′-end of the nucleic acid molecule and a BamH I (5′-GGATCC-3′) restriction site at the 3′-end of the nucleic acid molecule.

Fusion proteins are constructed by linking at least two nucleic acidsequences using standard cloning techniques as described e.g. bySambrook et al. 2001, Molecular Cloning: A Laboratory Manual. Thereforethe nucleic acid molecules encoding the peptide stretches were cleavedin a digest with the respective restriction enzymes Nde I and BamH I.Subsequently the cleaved nucleic acids encoding the peptide stretcheswere ligated into the pET21 b expression vector (Novagen, Darmstadt,Germany), which was also cleaved in a digest with the respectiverestriction enzymes Nde I and BamH I before.

Afterwards, the nucleic acid molecule encoding the endolysin OBPgpLYSderivative was cleaved in a digest with the restriction enzyme BamH Iand Xho I, so that the endolysin could be ligated into the pET21bexpression vector (Novagen, Darmstadt, Germany).

Thus, the nucleic acid molecule encoding the peptide stretch is ligatedinto the respective vector at the 5′-end of the nucleic acid moleculeencoding the endolysin OBPgpLYS derivative. Moreover, the nucleic acidmolecule encoding the endolysin OBPgpLYS derivative is ligated into therespective plasmid, so that a nucleic acid molecule encoding a His₆-tagconsisting of six histidine residues is associated at the 3′-end of thenucleic acid molecule encoding the endolysin.

The sequence of the endolysin-peptide-fusions was controlled viaDNA-sequencing and correct clones were transformed into E. coli T7Express lysY/Iq (New England Biolabs, Frankfurt, Germany) for proteinexpression.

Recombinant expression of the fusion proteins according to SEQ ID NO:55, 57, 63, 65, 67 is performed in E. coli T7 Express lysY/Iq (NewEngland Biolabs, Frankfurt, Germany). The cells were growing until anoptical density of OD600 nm of 0.5-0.8 was reached. Then the expressionof the fusion protein was induced with 0.5 mM IPTG(isopropylthiogalactoside) and the expression was performed at 37° C.for a period of 4 hours.

Cells were harvested by centrifugation for 15 min at 4000 g anddisrupted via sonication on ice. Soluble and insoluble fraction of theE. coli crude extract were separated by centrifugation (Sorvall, SS34,30 min, 15000 rpm). All proteins were purified by Ni²⁺ affinitychromatography (Äkta FPLC, GE Healthcare) using the C-terminal 6×His-tag, encoded by the pET21b vector.

The Ni²⁺ affinity chromatography is performed in 4 subsequent steps, allat room temperature:

-   -   1. Equilibration of the Histrap FF 5 ml column (GE Healthcare)        with up to 10 column volumes of Washing Buffer (20 mM imidazole,        1 M NaCl and 20 mM Hepes on pH 7.4) at a flow rate of 3-5        ml/min.    -   2. Loading of the total lysate (with wanted fusion protein) on        the Histrap FF 5 ml column at a flow rate of 3-5 ml/min.    -   3. Washing of the column with up to 10 column volumes of Washing        Buffer to remove unbound sample followed by a second washing        step with 10% Elution buffer (500 mM imidazole, 0.5 M NaCl and        20 mM Hepes on pH 7.4) at a flow rate of 3-5 ml/min.    -   4. Elution of bounded fusion proteins from the column with a        linear gradient of 4 column volumes of Elution Buffer (500 mM        imidazole, 0.5 M NaCl and 20 mM Hepes on pH 7.4) to 100% at a        flow rate of 3-5 ml/min.

Purified stock solutions of fusion proteins in Elution Buffer (20 mMHepes pH 7.4; 0.5 M NaCl; 500 mM imidazole) were at least 60% pure asdetermined visually on SDS-PAGE gels (data not shown).

EXAMPLE 4 Antimicrobial Activity of the Endolysin OBPgpLYS DerivativeModified with Various Peptide Stretches on the N-Terminus

Acinetobacter baumannii DSMZ 30007 and Pseudomonas aeruginosa PAO1pcells (Burn wound isolate, Queen Astrid Hospital, Brussels; Pirnay J Pet al. (2003), world-wide-web atncbi.nlm.nih.gov/pubmed/12624051?ordinalpos=3&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSumJ Clin Microbiol., 41(3):1192-1202) were used as test strains. Overnightcultures were diluted 10-fold in fresh LB medium and grown to OD₆₀₀=0.6.The culture was spun down and diluted 10-fold in dilution buffer (10 mMHEPES, 0.5 mM EDTA; pH 7.4). Bacteria were incubated at room temperaturewith each 10 μg undialyzed fusion protein at a final concentration of100 μg/ml in buffer (20 mM NaH₂P0₄—NaOH pH 7.4; 0.5 M NaCl; 0.5 Mimidazole). After 1 hour cell dilution series were made in PBS andplated on LB. Additionally, a negative control was plated using buffer(20 mM NaH₂P0₄—NaOH pH 7.4; 0.5 M NaCl; 0.5 M imidazole). The residualcolonies were counted after an overnight incubation at 37° C. Based onthe counted cell numbers the antibacterial activity as logarithmic units(=log₁₀N₀/N_(i) with N₀=number of untreated cells and N_(i)=number oftreated cells) was calculated (Table 5). All samples were replicated atleast in four fold.

TABLE 6 Antimicrobial activity of the OBPgpLYS derivative modified withvarious peptide stretches against gram-negative bacteria ActivityActivity Peptide stretch against against (N-terminal unlessAcinetobacter Pseudomonas otherwise baumannii aeruginosa Fusion proteinEnzyme part indicated) DSMZ 30007 PAO1p cells SEQ ID NO: 88 SEQ ID NO:87 — ++ + SEQ ID NO: 55 SEQ ID NO: 87 Ascaphine +++ Not (SEQ ID NO: 50)determined SEQ ID NO: 57 SEQ ID NO: 87 Apidaecine +++ Not (SEQ ID NO:51) determined SEQ ID NO: 63 SEQ ID NO: 87 Sarcotoxin IA +++ ++ (SEQ IDNO: 17) SEQ ID NO: 65 SEQ ID NO: 87 SMAP-29 +++ ++ (SEQ ID NO: 12) SEQID NO: 67 SEQ ID NO: 87 Cecropin A +++ +++ (SEQ ID NO: 15) Abreviations:+: 1 log; ++: 2-3 log; +++: 4 or more logs; not determined means thatthis strain was not tested with the respective fusion protein.

The fusion proteins in Table 6 without any tag and linker were alsotested with the activity assays described above. They all showedantimicrobial activity against the used bacterial strains in Table 6.

EXAMPLE 5 N-Terminal Antibacterial Peptide Fusion to Endolysin ofPseudomonas putida Phage OBP

OBPgpLys derivative, the modular endolysin of P. putida phage OBP, wasN-terminally fused to a set of natural antibacterial peptide tags (Table7) in order to investigate its anti Gram-negative activity.

TABLE 7 List of antibacterial peptide tags which were fused to the OBPgpLYS derivativeDescription + Nucleic acid Tag size Amino acid sequence sequenceReference α4-helix of  Amphipathic PNRAKRVITTFRT SEQ ID NO: 95Matthews et T4-lysozyme helix (SEQ ID NO: 68) al., 1974* (13 aa)Pentapeptide Hydrophobic FFVAP SEQ ID NO: 96 Briers Y (designed) (5 aa)(SEQ ID NO: 18) (not published Artilysin1 Hydrophobic GFFIPAVILPSIAFLIVPSEQ ID NO: 97 Walmagh, M. (designed) (18 aa) (SEQ ID NO: 70)(Not published) Artilysin 2 Amphipathic GKPGWLIKKALVFKKLIRRPLKRLASEQ ID NO: 98 Walmagh, M (designed) helix (25 aa) (SEQ ID NO: 71)(Not published) Parasin 1 Alpha-helical KGRGKQGGKVRAKAKTRSSSEQ ID NO: 99 Park, Y et peptide (SEQ ID NO: 72) al., 1998** (19 aa)Lycotoxin 1 Amphiphatic IWLTALKFLGKHAAKKLAKQQLSKL SEQ ID NO: 100Yan & Adams, helix (25 aa) (SEQ ID NO: 73) 1988*** *Matthews, B. W. andRemington, S. J. (1974). The three dimensional structure of the lysozymefrom bacteriophage T4. Proc. Natl. Acad. Sci. U.S.A., 71: 4178-4182 **InYup Park, Chan Bae Park, Mi Sun Kim, Sun Chang Kim (1998). Parasin I, anantimicrobial peptide derived from histone H2A in the cat¢sh,Parasilurus asotus. FEBS Letters 437 258-262 ***Yan, L and Adams, M. A.(1998). Lycotoxins, Antimicrobial Peptides from Venom of the WolfSpider, Lycosa carolinensis J. Biol. Chem, 273: 2059-2066.Methodology of Tag Modification of the OBPgpLys Derivative

Except for the pentapeptide tag, all antibacterial peptide tags werefused to the ORF which encodes for the OBPgpLYS derivative using anadapted version of the Ligation Independent Cloning (LIC) as e.g.described in Berrow et al. 2007. Here fore, an unique Ecl136IIrestriction site was inserted in front of the WT endolysin gene by atail PCR with a specific designed 5′ primer(5′-GGAATGGGGAGCTCCTCCAAAAATAGCGAGAAG-3′; SEQ ID NO:102) and thestandard OBPgpLys derivative reverse primer(5′-AACTATTCCGTGTGCTTTCTTTGT-3′; SEQ ID NO:103) on pure genomic DNA ofphage OBP. This extended fragment was then ligated in the pEXP5CT/TOPO®expression vector (Invitrogen, Carlsbad, Calif., USA) by following theTA cloning protocol of the manufacturer. Pure plasmid was cutted once inan Ecl136II restriction digest and hybridized peptide cassettes (createdby hybridization of primer pairs, see Table 8) were inserted into thecutted plasmid without a necessary ligation step (LIC). For theN-terminal pentapeptide tag fusion a tail PCR with an extended 5′ primerwhich encodes for this pentapeptide (5′-ATGGGATCCTTCTTCGTAGCACCGGGCTCCTCCAAAAATAGCGAGAAG-3′; SEQ ID NO:104) and the standard OBPgpLysderivative reverse primer (5′-AACTATTCCGTGTGCTTTCTTTGT-3′; SEQ IDNO:103) was applied on phage OBP genomic DNA. Correct insertion of thefragments in the expression vector was verified by sequencing analysisbefore introducing the construct into a suitable Escherichia coliBL21(DE3)pLysS expression strain.

TABLE 8 Used primer pairs for hybridization of antibacterial peptide tags to ORFencoding the OBPgpLys derivative Tag forward primer reverse primerα4-helix of 5′ TTGGAATGGGGAGCCCGAACCGTGCAAAACG 5′TATTTTTGGAGGAGCCGGTACGGAAGGTGGTGAT T4-lysozymeTGTAATCA 3′; SEQ ID NO: 105 TACACGTT 3′; SEQ ID NO: 106 Artilysin1 5′TTATGGGCTTCTTCATCCCGGCAGTAATCCTGC 5′ TATTTTTGGATCTGCCGCCCGGTACGATCAGGAAT(designed) CCTCCA 3′; SEQ ID NO: 107GCGATGGAGGGCAGGATT 3′; SEQ ID NO: 108 Artilysin 2 5′TTATGGGCAAACCGGGCTGGCTGATCAAAAG 5′ TATTTTTGGATCTGCCGCCTGCCAGTCTCTTCAGC(designed) GCACTGGTATTCAAGA 3′; SEQ ID NO: 109GGACGACGGATCAGTTTCTTGAATACCAG 3′; SEQ ID NO: 110 Parasin 1 5′TTGGAATGGGGAGCAAAGGCCGTGGCAAGCA 5′ TATTTTTGGAGGAGCCTGAGGAACGGGTCTTTGCTGGGAGGCAAAGTACGTG 3′; SEQ ID NO: 111 TTTGCACGTACTTTGC 3′; SEQ ID NO: 112Lycotoxin 1 5′ GGAATGGGGAGCATCTGGCTGACCGCACTGA 5′TATTTTTGGAGGAGCCCAGTTTGGATAATTGCTGT AATTCCTCGGCAAACACGCCGCAA 3′; SEQ IDTTTGCCAGTTTCTTTGCGGCGTGTT 3′; SEQ ID NO: 113 NO: 114Large Scale Recombinant Expression of Modified OBPgpLYS DerivativeFusion Variants

Standard expression is performed in Lysogeny Broth (LB) in exponentiallygrowing cells (OD600 nm=0.6) induced with 1 mMisopropyl-beta-D-thiogalactopyranoside. Expression parameters liketemperature, time and expression strain varied on a protein specificbasis in order to optimize the soluble expression levels of the modifiedendolysins (see Table 9).

For purification, cells from an expression culture (500-600 ml) areharvested (4500 rpm, 30 min, 4° C.) and resuspended in 1/25 volumes oflysis buffer (10 mM imidazole, 20 mM NaH2PO4, 0.5 M NaCl, pH 7.4). Thissuspension is frozen/thawed three times prior to sonication (8×30 s,amplitude 40% on a Vibra Cell™, Sonics, Dandurry, Conn., USA) andfiltered through 0.45 and 0.22 μm Durapore membrane filters (Millipore,Billerica, Mass., USA). Purification of the His-tagged fusion proteinwas performed by a one-step protocol employing Ni2+—affinitychromatography (HisTrap HP 1 ml column, GE Healthcare, Buckinghamshire,UK) according to the manufacturer's instructions. The Ni2+ affinitychromatography is performed in 4 subsequent steps, all on roomtemperature:

-   -   1. Equilibration of the Histrap HP 1 ml column (GE Healthcare)        with 10 column volumes of Washing Buffer (60 mM imidazole, 0.5        mM NaCl and 20 mM NaH2P04-NaOH on pH 7.4) at a flow rate of 0.5        ml/min.    -   2. Loading of the total lysate (with wanted endolysin) on the        Histrap HP 1 ml column at a flow rate of 0.5 ml/min.    -   3. Washing of the column with 15 column volumes of Washing        Buffer at a flow rate of 1 ml/min.    -   4. Elution of bounded endolysin from the column with 10 column        volumes of Elution Buffer (500 mM imidazole, 0.5 M NaCl and 20        mM NaH2P04-NaOH on pH 7.4) at a flow rate of 0.5 ml/min

The wash buffer included a low imidazole concentration which varied onprotein specific base to ensure higher purity of the protein (see Table9). The total yields of recombinant proteins per liter E. coliexpression culture is also shown in Table 3. The values were determinedby spectrophotometric measurement of the protein concentration and thetotal volume of the purified stock solution at a wavelength of 280 nm.Purified stock solutions were at least 60% pure as determined visuallyon SDS-PAGE gels.

TABLE 9 Expression parameters and obtained protein yields per literexpression culture of N-terminal modified endolysins. RP = E. coliBL21(DE3)pLysS Codon min RP strain, RIL = E. coli BL21(DE3)pLysS CodonPlus RIL strain Modified Temper- Protein Yield [imidazole] endolysinature/time (in mg/l) (in mM) α4-OBPgpLys 16/overnight 1.28 60 (SEQ IDNO: 75) Pentapeptide- 16/overnight 1.10 65 OBPgpLys (SEQ ID NO: 77)Artilysin1- 16/overnight <0.1 50 OBPgpLys (SEQ ID NO: 79) Artilysin2-16/overnight 1.32 50 OBPgpLys (SEQ ID NO: 81) Parasin1- 16/overnight0.38 50 OBPgpLys (SEQ ID NO: 83) Lycotoxin1- 16/overnight 1.71 50OBPgpLys (SEQ ID NO: 85)In Vitro Antibacterial Activity and Host Range of Modified OBPgpLysDerivative Variants

Exponential growing Gram-negative bacterial cells (OD600 nm=0.6) were100-fold diluted to a final density of about 106 cells/ml and incubatedfor 30 minutes at room temperature without shaking with the differentmodified OBPgpLYS derivative variants. After incubation cell suspensionswere diluted three times (respectively 105-104-103 cells/ml) and 100 μlof each dilution was plated out on LB-medium. The residual colonies werecounted after an overnight incubation on 37° C. Based on the countedcell numbers the antibacterial activity as the relative inactivation inlogarithmic units (=log 10N₀/N_(i) with N₀=number of untreated cells andN_(i)=number of treated cells, both counted after incubation) iscalculated (Table 10). All samples were replicated in threefold.Averages +/− standard deviations are represented.

TABLE 10 In vitro antibacterial activity of different modified OBPgpLYSderivative variants on a range of exponential growing Gram-negativespecies with 0.5 mM EDTA. Initial density is 10⁶ cells/ml and incubationproceeds for 30 minutes without shaking at RT. Protein concentration is1500 nM, except for Artilys1-OBPgplys (800 nM). Salmonella P. aeruginosaP. putida E. coli typhimurium PAO1p G1 Xl-1 LT2 1500 nM α4-OBPgpLys ++++ ++ + (SEQ ID NO: 75) 1500 nM Pentapeptide- ++ +++ ++ + OBPgpLys (SEQID NO: 77) 800 nM Artilysin1- Not determined ++ + + OBPgpLys (SEQ ID NO:79) 1500 nM Artilysin2- ++ ++ ++ + OBPgpLys (SEQ ID NO: 81) 1500 nMParasin1- +++ +++ +++ ++ OBPgpLys (SEQ ID NO: 83) 1500 nM Lycotoxin1- +++++ ++ + OBPgpLys (SEQ ID NO: 85) 1500 nM OBPgpLYS + + + + (SEQ ID NO:88) Abreviations: +: about 0.5 log; ++: 1-2 log; +++: 3-4 or more logs;not determined means that this strain was not tested with the respectivefusion protein.

The invention claimed is:
 1. A vector comprising a polynucleotideencoding a polypeptide and a nucleic acid that is heterologous to thepolynucleotide, wherein the polypeptide comprises the amino acidsequence of SEQ ID NO: 1, or a fragment thereof, wherein the fragmentcomprises an amino acid sequence selected from the group consisting ofSEQ ID NO: 4 and 5, or comprises the amino acid sequences of SEQ ID NO:4 and
 5. 2. An isolated host cell comprising the vector according toclaim
 1. 3. A composition comprising the vector of claim
 1. 4. A vectorcomprising a polynucleotide encoding a fusion protein and a nucleic acidthat is heterologous to the polynucleotide, wherein the fusion proteincomprises (i) a polypeptide comprising the amino acid sequence of SEQ IDNO: 1, or a fragment thereof, wherein the fragment comprises an aminoacid sequence selected from the group consisting of SEQ ID NO: 4 and 5,or comprises the amino acid sequences of SEQ ID NO: 4 and 5, and (ii) apeptide fused to said polypeptide at the N- or C-terminus, wherein saidpeptide is a cationic peptide, polycationic peptide, amphipathicpeptide, sushi peptide, defensin, hydrophobic peptide and/or anantimicrobial peptide.
 5. An isolated host cell comprising the vectoraccording to claim
 4. 6. The vector according to claim 4, wherein saidpeptide comprises 5 to 100 amino acid residues, 5 to 50 amino acidresidues, or 5 to 30 amino acid residues.
 7. The vector according toclaim 4, wherein said peptide is a cationic and/or polycationic peptide,wherein said cationic and/or polycationic peptide comprises at least oneamino acid residue selected from the group consisting of arginine,histidine and lysine residues, optionally wherein at least 70% of theamino acid residues in said peptide are arginine, histidine and/orlysine residues.
 8. The vector according to claim 4, wherein the peptideis an amphipathic peptide, wherein said amphipathic peptide comprises atleast one positively charged amino acid residue selected from the groupconsisting of lysine, arginine and histidine residues, combined to atleast one hydrophobic amino acid residue selected from the groupconsisting of valine, isoleucine, leucine, methionine, phenylalanine,tryptophan, cysteine, alanine, tyrosine, histidine, threonine, serine,proline and glycine residues, optionally wherein at least 70% of theamino acid residues in said amphipathic peptide are either arginine orlysine residues and at least 30% of the amino acid residues in saidamphipathic peptide are valine, isoleucine, leucine, methionine,phenylalanine, tryptophan, cysteine, alanine, tyrosine, histidine,threonine, serine, proline or glycine residues.
 9. The vector accordingto claim 4, wherein the peptide comprises an amino acid sequenceselected from the group consisting of SEQ ID NO: 6-38 and
 39. 10. Thevector according to claim 4, wherein said fusion protein comprises anamino acid sequence selected from the group consisting of SEQ ID NO: 43and
 49. 11. A composition comprising the vector according to claim 4.12. The vector according to claim 1, wherein the polypeptide comprises afragment of the amino acid sequence of SEQ ID NO: 1, wherein thefragment comprises an amino acid sequence selected from the groupconsisting of SEQ ID NO: 4 and 5, or comprises the amino acid sequencesof SEQ ID NO: 4 and
 5. 13. A vector comprising a polynucleotide encodinga polypeptide and a nucleic acid that is heterologous to thepolynucleotide, wherein the polypeptide comprises the amino acidsequence of SEQ ID NO: 86 or
 87. 14. The vector according to claim 1,wherein the polypeptide further comprises a tag, optionally wherein thetag is a His₆-tag.
 15. The vector according to claim 14, wherein saidpolypeptide comprises the amino acid sequence according to SEQ ID NO:47.